The PowerShell components of Exchange – either on-premises or hosted – aren't amazing at "cracking open" a mailbox to get at its contents. Do you have a way of doing this against your local Exchange server by using PowerShell?

I was able to find this script which works on a on premises Exchange, have not had a chance to test it against Office365 yet since I am fighting a number of "fires" today (I believe this is from Shay Levy):